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Horizontal Grid Size Selection and its Influence on Mesoscale Model Simulations

The use of two-dimensional spectral analysis applied to terrain heights in order to determine characteristic terrain spatial scales and its subsequent use for the objective definition of an adequate grid size required to resolve terrain forcing are presented in this paper. In order to illustrate the influence of grid size, atmospheric flow in a complex terrain area of the Spanish east coast is simulated by the Regional Atmospheric Modeling System (RAMS) mesoscale numerical model using different horizontal grid resolutions. In this area, a grid size of 2 km is required to account for 95% of terrain variance. Comparison among results of the different simulations shows that, although the main wind behavior does not change dramatically, some small-scale features appear when using a resolution of 2 km or finer. Horizontal flow pattern differences are significant both in the nighttime, when terrain forcing is more relevant, and in the daytime, when thermal forcing is dominant. Vertical structures also are investigated, and results show that vertical advection is influenced highly by the horizontal grid size during the daytime period. The turbulent kinetic energy and potential temperature vertical cross sections show substantial differences in the structure of the planetary boundary layer for each model configuration

© Journal of Applied Meteorology and Climatology, 1999, vol. 38, núm. 9, p. 1311-1329

American Meteorological Society

Author: Salvador, Rosa
Calbó Angrill, Josep
Millán, Millan M.
Date: 1999
Abstract: The use of two-dimensional spectral analysis applied to terrain heights in order to determine characteristic terrain spatial scales and its subsequent use for the objective definition of an adequate grid size required to resolve terrain forcing are presented in this paper. In order to illustrate the influence of grid size, atmospheric flow in a complex terrain area of the Spanish east coast is simulated by the Regional Atmospheric Modeling System (RAMS) mesoscale numerical model using different horizontal grid resolutions. In this area, a grid size of 2 km is required to account for 95% of terrain variance. Comparison among results of the different simulations shows that, although the main wind behavior does not change dramatically, some small-scale features appear when using a resolution of 2 km or finer. Horizontal flow pattern differences are significant both in the nighttime, when terrain forcing is more relevant, and in the daytime, when thermal forcing is dominant. Vertical structures also are investigated, and results show that vertical advection is influenced highly by the horizontal grid size during the daytime period. The turbulent kinetic energy and potential temperature vertical cross sections show substantial differences in the structure of the planetary boundary layer for each model configuration
Format: application/pdf
ISSN: 1558-8432 (versió paper)
1558-8424 (versió electrònica)
Document access: http://hdl.handle.net/10256/7692
Language: eng
Publisher: American Meteorological Society
Collection: Reproducció digital del document publicat a: http://dx.doi.org/10.1175/1520-0450(1999)038<1311:HGSSAI>2.0.CO;2
Articles publicats (D-F)
Is part of: © Journal of Applied Meteorology and Climatology, 1999, vol. 38, núm. 9, p. 1311-1329
Rights: Tots els drets reservats
Subject: Meteorologia
Meteorology
Anàlisi espectral
Spectrum analysis
Title: Horizontal Grid Size Selection and its Influence on Mesoscale Model Simulations
Type: info:eu-repo/semantics/article
Repository: DUGiDocs

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